Vehicle cameras are used for representing a vehicle environment on a display and for vehicle assistance functions for gathering information on the vehicle environment.
Monochromic cameras are able to record different brightness values and make possible high-sensitivity resolution. They are used in night vision systems, for example.
For one thing, color cameras make possible a colorful reproduction of the environment, and for another, an evaluation of various color data. Thus, light assistance functions for vehicles are known in which a vehicle camera ascertains whether other traffic participants are located in a relevant region ahead of the vehicle, and, as a function of this ascertainment, the headlights are automatically switched over from high beam to low beam. For this purpose, sensors are generally used having a color mask which makes possible a color differentiation, especially between red and white, so as to be able to recognize the generally red tail lights and the generally white low beam lights and high beam lights of other vehicles, and distinguish them from one another, even weak red lights, for example, being able to be distinguished from white reflections from other objects.
Such color masks in front of imager sensors and imager chips consequently make possible that different color data are able to be gathered on adjacent pixels. The sensor pixels, in this instance, each supply a scalar value, which, for instance, may be a color value such as R, G, or B, or in the case of a transparent filter pixel, even an intensity value. Thus, standard Bayer pattern masks are known in which every other filter pixel of the color mask is green and these green filter pixels are ordered, distributed in an alternating chessboard-like manner over the matrix arrangement of the filter pixels.
In the other matrix positions blue and red filter pixels are situated, lines having green and blue pixels alternating with lines having red and green pixels. This makes possible a complete color differentiation, i.e. an interpretation into the colors red-blue-green. A disadvantage is, however, the reduction in high-sensitivity resolution compared to that of a monochromic image sensor by a factor of 2. In the case of reduced filter masks, some color pixels of this standard Bayer pattern are omitted, so that transparent pixels remain at their place, whereby the high-sensitivity resolution is increased. The color data obtained in the image signals gathered, in addition to the detection of red tail lights, are also able to be utilized, if necessary, to detect traffic signs having typical colors.
Retroactive coloring of pictures is known, for example, from graphics, or from the retroactive processing of old black and white films, retroactive color data being used in each case, that are typically known to an observer, and that are able to be taken over, in automated fashion, in subsequent pictures of a film. It is basically true that color data that are not present are not able to be gathered retroactively, for instance, for coloring black and white pictures.
Japanese document JP 2004304706 A shows a color filter having green, white, red and blue color filter segments, of which the white segments, that are used for a luminescence signal, occupy, chessboard-like, every other matrix position, and the color segments occupy the other remaining half of the matrix positions. In this connection, lines having white and green segments alternate with lines having white, red and blue segments, so that at the corners, each green segment is situated diagonally opposite respectively two blue segments and two red segments. The document also describes an interpolation method for evaluating the image signals that were taken while using such a color mask.